This invention generally relates to electric terminals, and more specifically to electric terminals employed to deliver electric power from an external source thereof to electrical conductors disposed within a shell of an electrically operated apparatus.
Electric terminals are often used to conduct an electric current from an external source to a plurality of electrical conductors located inside a shell or housing of an electrically driven apparatus, for example a hermetically or semi-hermetically sealed compressor. Such terminals commonly comprise a body and a plurality of terminal pins longitudinally extending through the body. The body, in turn, includes a metallic mounting plate and plurality of electrically nonconductive pieces. The mounting plate is used to secure the electric terminal to the shell or housing of the electrically operated apparatus; and the electrically nonconductive pieces extend above, below, and within the mounting plate and substantially enclose central portions of the terminal pins to insulate electrically the pins from each other, the mounting plate, and the shell or housing.
In many instances it is necessary to prevent fluid flow through the electric terminal. For example, if the terminal extends through the shell of a hermetically or semi-hermetically sealed compressor filled with vapor at greater than ambient pressure, it is necessary to prevent vapor leakage from the interior of the shell through the electric terminal. For this reason, the different pieces comprising the terminal may be compressed together into fluid tight, pressure contact. This pressure contact may be achieved by longitudinally compressing the body of the terminal inward between top and bottom elements connected to or forming a part of the terminal pins. For example, the terminal pins may include bottom, transversely extending flange portions, and the body of the electric terminal may be compressed between these flanges and a plurality of nuts threadably engaging upper portions of the terminal pins and held thereby in pressure contact against the top surface or surfaces of the body.
In this manner, the various pieces comprising the body are securely held together and brought into pressure contact with each other and with the terminal pins, retarding fluid flow along adjacent surfaces of the electric terminal. Moreover, the terminal pins themselves are securely held in place relative to the body of the terminal. Despite this pressure contact, however, if the electric terminal is subjected to abusive conditions, water or other contaminants may leak into the electric terminal, and these contaminants may cause electrical arcing between central portions of the terminal pins and the mounting plate. This arcing may corrode central portions of the terminal pins, and eventually a terminal pin may break into two separate pieces.
With the above-described type of electric terminal, where the pieces of the terminal body are compressed together between elements connected to or forming a part of the top and bottom portions of the terminal pins, if the central portion of a terminal pin breaks, the forces holding the terminal body together are reduced. Consequently fluid may more readily leak into the terminal, particularly in the area of the broken pin. If the electric terminal is employed with a compressor filled with vapor at greater than ambient pressure, the vapor may leak into the terminal and thence force the broken pieces of the pin out of the terminal. When this happens a relatively large leak path is established through the terminal and the vapor within the compressor may escape through this leak path, eventually resulting in a nearly complete loss of vapor.